1. Field of the Invention
The present invention relates to electrometallurgy and more particularly to processes for the electroslag remelting of consumable electrodes, for instance two consumable electrodes at a time.
2. Description of Prior Art
Commonly known is a process of electroslag remelting several consumable electrodes simultaneously in a cooled mold, the process being associated with the formation of a slag and metal baths, the consumable electrodes in said process being connected to unlike poles of a power source and secured expediently in a common electrode holder.
The simultaneous melting of several consumable electrodes is best suited for melting ingots of large cross-sections, e.g. 1200.times.400 mm.
However, the consumable electrodes produced by casting, rolling or forging are not uniform in terms of their cross-sectional areas although within production tolerances. Moreover, the consumable electrodes are slightly curved along their length thereby resulting in their being mounted at a distance from the mold walls. Besides, during melting, the consumable electrodes are not uniformly heated throughout their length and over their cross-sections by electrical currents flowing through them; also, the electrodes are not uniformly cooled by natural gases that may be liberated by the electrodes.
As a result, as shown by investigations, the depth of immersion of the consumable electrodes melted at one and the same time changes nonuniformly and the resulting discrepancy (unbalance) adversely affects the quality of the ingots being handled.
Naturally, the portion of the electrode melting adjacent the surface of the slag bath is subjected to heavy oxidation and contaminates the metal being remelted. The portion of the electrode immersed to a greater depth exerts on the other hand a negative influence on the formation of the ingot surface.
It may also happen that the major (larger) fraction of electrical current flowing through the electrodes will pass not through the ingot being deposited but through the slag between the electrodes.
The phenomenon is also observed in electroslag remelting with equalizing currents flowing through the ingot when different currents pass through the consumable electrodes.